Heat assisted magnetic recording (HAMR) technology continues to be developed to replace conventional perpendicular magnetic recording (CPMR) technology and deliver higher recording densities. At the same time, HAMR media is typically rougher than CPMR because of differences in structure and process conditions. Advanced CPMR structures use multiple layers ending with a capping layer which is significantly less segregated than the layers positioned underneath the capping layer. Although not its primary function, the capping layer lowers roughness in CPMR media. In addition, the CPMR process temperature is much lower than HAMR process temperature, which leads to less tendency of grain coarsening and better control of the microstructure.
The rougher media for HAMR can lead to higher flight height and thus poorer recording performance. In addition, the rougher media for HAMR can also require thicker overcoats for corrosion protection, which results in poorer recording performance because of the larger magnetic spacing. However, the media roughness is preferably lower for higher density applications. As such, one target goal for HAMR media is for media roughness to be below that of CPMR media. The HAMR media also displays higher DC noise compared to CPMR media, which can present a number of other problems.
A capping layer is often proposed to address the problems noted above. However, capping layer deposition in HAMR media is not straightforward and frequently results in a number of other problems, including rougher media and worse overall performance. This is due, at least in part, because it is hard to achieve the desired structure with the choice of materials that would also deliver the required thermo-magnetic properties. For example, the high temperature deposition of HAMR media leads to accelerated grain coarsening in layers that do not contain enough segregants. In addition, epitaxially growing capping layers on a magnetic recording layer such as a L10 FePt base granular film is not straightforward. Accordingly, a system and method for forming a capping layer in magnetic media that addresses these problems is needed.